ASP.NET Core 3.1 - PostAsync/PostAsJsonAsync method in Integration Test always returns Bad Request

Question

This is my register method inside the AuthController.

[HttpPost(ApiRoutes.Auth.Register)]
public async Task<IActionResult> Register(UserRegistrationRequest request)
{
    var authResponse = await _authService.RegisterAsync(request.Email, request.Password);

    if (!authResponse.Success)
    {
        return BadRequest(new AuthFailedResponse
        {
            Errors = authResponse.Errors
        });
    }

    return Ok(new AuthSuccessResponse
    {
        Token = authResponse.Token,
        RefreshToken = authResponse.RefreshToken
    });
}

I'm trying to call this method by using TestClient.PostAsync() method, unfortunately it always returns Bad Request. I've already tried calling the TestClient.PostAsJsonAsync(ApiRoutes.Auth.Register, user) method by importing Microsoft.AspNet.WebApi.Client package, the result is the same.

var user = new UserRegistrationRequest
    {
        Email = "user1@testtest.com",
        Password = "P@ssw0rd1!!!!!"
    };

var response = await TestClient.PostAsync(
        ApiRoutes.Auth.Register,
        new StringContent(JsonConvert.SerializeObject(user), Encoding.UTF8)
        {
            Headers = { ContentType = new MediaTypeHeaderValue("application/json") }
        });

Answer 1

You are missing the FromBody attribute from you action parameter. When you are sending json data to a controller that will be part of the request body. You can tell to the controller how to bind the incoming data, in your case from the body. So you code should look like:

public async Task<IActionResult> Register([FromBody]UserRegistrationRequest request)
{
    …
}

You could read more about bindings in the official documentation.